LessLoss Firewall for Headphones

by Dawid Grzyb / July 16, 2024

The LessLoss Firewall technology has been around for many years. It underwent several iterations and until recently it was reserved for power lines, internal wiring usage, and speakers. Now it’s available for headphones and I had to know what it does in this application. Enjoy!

The wall

These days we know a fair bit about the harmful impact of noise on sound quality. The more of it we can trim, the better our setups perform, which makes noise rejection a powerful and desirable thing. The awareness of this action as the effective route to the higher-tiered sound is the common ground for many manufacturers and their clients. Some audio houses specialize in passive means designed to combat noise, others go active. Some put more effort into this subject than others, and there’s also a handful of those quite obsessed with it. Here the Lithuanian company LessLoss is the notable standout. Nearly all products in this roster have been designed specifically with noise removal in mind. Over the years I had the pleasure of sampling quite a few LessLoss solutions with excellent results. That’s why my system features a small army of stuff infused with the LessLoss tech; C-MARC cables and Firewall modules.C-MARC wiring comprises a unique geometry based on two counter-polarized, then fractally replicated coils of the same diameter and step; one turned clockwise and the other twisted in the opposite direction. They superimpose mutually to form a bucking-coil connection originally developed in the 1930s. Noise induced on hundreds of these balanced strands is electrically cancelled due to their opposite polarity and geometry, which results in high S/N ratio. RCAs, XLRs, power cords and speaker veins in my system are exclusively C-MARCs. The Firewall is a specialist fully passive signal conditioner that goes about its business without caps and coils. Upon connecting a single such module to an amp, it’ll essentially see only 20mm2 of highly conductive solid core copper and that’s it. This cross-sectional area is substantial enough to not have any impact on signal flow, resistance or the connected load’s impedance. Not only this, Firewalls also work their magic inside i.e. power distributors and speaker crossovers.

Four copper rods inside each Firewall’s translucent resin body undergo the company’s in-house developed Entropic processing, which drastically ages these parts and results in their unique matte look. This treatment also changes the conductor’s internal structure, so it becomes directional and far less susceptible to micro-vibrations thus quieter. That’s not the best part. Entropy stands for gradual decline into unavoidable decay. This copper gains new properties at a cost of becoming so old that it can too easily deform. Think far more than a human’s lifetime of constant usage, but compressed into several days of extensive processing, which makes conductive rods highly pliable if unsupported. The crystalline resin cylinders lock these delicate bits in place, so that their integrity remains intact and the entire module becomes robust. Each copper rod pair is surrounded by the crucial finned parts, which are the latest LessLoss Firewall incarnates. This in-house developed noise-killing technology underwent many iterations over the years. Now it incorporates the DMLS (Direct Metal Laser Sintering) processing and high-powered ytterbium fiber lasers, which allow for welding alloy powder into required 3D objects from particles as small as 10 nanometers. The finned cylinders aren’t physically connected with copper conductors inside them. Their interaction however involves magnetic fields and that’s all we know. The rest is LessLoss’ sweet secret. This also tells us that these ingredients have to align perfectly to maximize the noise-trimming effect, otherwise this fundamental goal is compromised. Firewalls in their modular form have been installed inside both my speaker sets and outlet multipliers. I also use one external Firewall set for the speaker set I currently listen to.The LessLoss roster lists finished C-MARC and Firewall products just next to their core DIY-ready ingredients, respectively sold per meter and module. The manufacturer offers one three-legged Firewall 640x unit ($320/ea) meant for applications related to power, while the remaining three loudspeaker versions take the form of single/dual/quad sets of four runs, and are priced at $800/1’600/3’200 respectively. This technology already proved great for power lines and speakers, so seeing it applied elsewhere was just a matter of time. Today’s that day. Upon learning about the latest Firewall, I looked forward to a box groomed for small-signal jobs, i.e. in-between a DAC and preamp. Team LessLoss detoured towards a box alright, but for headphones. It’s large, heavy and packed with more Firewalls than I thought it would. The interconnect version, I’m told, is right around the corner.

When I think about a headphone accessory, I see a fully portable dongle device a’la iFi audio iEMatch that mounts to a headphone cable and becomes its extension. The latest Firewall is anything but. It measures 23 x 11 x 4cm and weighs stout 2,1kg, so is meant for stationary use. Priced at $4’918, it is also very expensive. That kind of money easily gets us excellent cans, amp or DAC. Such mindset dearly misses the point, however. The LessLoss newcomer is for headfi’s high rollers who already have these main bases done and dusted and irreplaceable. Ditto power tweaks, cables and anti-vibration pucks. That kind of audience is always on a lookout for means to improve their already very fancy setups. As a unique design which doesn’t have a real sparring partner as far as I can tell, this story’s unique signal cleanser promises improvements in systems without any wiggle room left for other more standard tweaks. It’s also costly for a reason.Although I couldn’t get inside my LessLoss loaner, its interior isn’t secretive. Four dual Firewall modules nested therein are worth $1’600 alone and make this a balanced affair. This critical cluster connects to the two circuit boards and those to 4-pin XLR i/o via entropic-processed copper rods. One of each a male input and female output prevent usage any other than intended. The Firewall’s inside doesn’t hide anything else because there’s no need for that. The passive nature of this technology itself means that it works without external power. A signal traveling from an amp enters the core Firewall component where it is conditioned and then forwarded to headphones. That’s all there is to it really, but the devil’s in the details. All parts including sockets underwent the company’s Entropic procedure, while their milled brass housing visible under all the black panels together with resin infused Kraft paper outer shell is part of the potent anti-vibration measure which also explains the product’s weight. These satin surfaces aren’t regular either. LessLoss has been a huge advocate of Panzerholz, which is known throughout the industry for its superb self-damping properties. The latest Firewall box has all of its six walls built upon multiple extremely hard and dense layers of resin-infused Kraft paper, which as I’m told is even better than Panzerholz where it matters. The result feels nice and most definitely like a costly premium object.

As a passive device that goes between our headphones and amp of choice, today’s Firewall was a breeze to use. So much so in fact that I don’t think that I’ve ever sampled a product any easier to dis/engage than this one. Really. It connected to the Enleum AMP-23R via a short pigtail terminated with a 6,3mm plug on one end, and a female 4-pin XLR on the other. A headphone cable finished with a male 4-pin XLR connected this Firewall to HiFiMan Susvara cans. It’s worth noting that I DIY-ed both these harnesses for the purpose of this review. They’re based on LessLoss’ own entropic-processed C-MARC wiring specifically for cans. In its commercial form it’s just around the corner, but that’s all I can say for now. Moving on, my entire setup features exclusively various C-MARCs and is powered from the same company’s power distributor. To compare that system’s sound with/out the latest Firewall, I had to just unplug both 4-pin XLRs from it and then connect them, so that the Enelum amp saw the Susvara directly. That said, this routine removed any downtime and was a simple as it gets. Heck, I didn’t even have to adjust volume or move away from the listening chair. Life was peachy.I’m no stranger to the Firewall technology. The more these modules are in use, the more their effectiveness compounds, specifically backdrop cleanliness, spatial focus and moisture. The first notion of this additive action I had several springs ago upon connecting the external Firewalls to the Boenicke W11 SE+ floorstanders, which already have these parts applied internally to their crossovers. Just one swap with/out the external units sufficed to track meaningful and beneficial changes; higher instrumental and vocal hydration, more grounded sound, rounder less chiseled edges, tighter bass, improved clarity, less grain and all virtual shapes rendered more precisely on a background that felt sensibly more pristine. This one sentence encapsulates the general Firewall MO. These are the perks to expect once the Lithuanian inline cleansers are hired to banish excess noise. To my experience, their efficacy is alike no matter whether they’re used as external or internal means. The LessLoss technology inside them is the same and what really matters. To make it more accessible, the manufacturer simply wrapped it into several physical forms which other audio makers easily fit inside their own products. Boenicke Audio and sound|kaos are two notable adopters with lots of street cred among audio enthusiasts.

Not only do I deem Firewalls very useful with all kinds of speakers, I haven’t yet encountered one that wouldn’t audibly benefit from such assistance. The purist rear horn-loaded wideband breed is known for its direct quicksilvery aroma as much as somewhat shouty lean attitude that can also be shy on bass. To offset that, a suitable amp companion is a must. More importantly, these crossoverless loads are inherently highly revealing, in the sense that they track and magnify even tiniest changes in our setups more clearly than most regular two- or three-ways. Ever since the Firewalls’ arrival in early 2020 I had the pleasure of guesting five wideband specimens. Each was very fond of these accessories, which is hardly a surprise considering their easily traceable input. Rounder and fleshier vocals, wider color palette, increased fullness, longer decay and weight upstairs, higher clarity and lesser shout, edginess and grit are the benefits most widebander aficionados would appreciate and enjoy. All things considered, I can’t fault speaker Firewalls for anything in particular where it counts. In my book, these devices are free from any sonic downsides and really child’s play to use.This is also the very reason why in my system I see LessLoss Firewalls for speakers as necessities rather than accessories. Their work may seem mild at first, but disengaging them after a week or two of constant use is plainly painful. Then it hits us how much these small barrels actually contribute, or rather how much is lost upon taking them away. It seems fitting to call them highly advanced inline filters, but not necessarily accurate. Here Srajan already pointed out that Firewalls condition signal to reveal information previously held hostage by residual noise. Their additive work is thus opposite to subtractive filtering. Since I fully agree, in my own review I wrote that Firewalls don’t add anything audible to a system’s voicing that is not already there in the first place. These aren’t tools meant to alter its core flavor. Instead they show how it fares without the well-known byproducts of noise; harshness, sharpness, leanness and grit. This is why listeners who use a Firewall product in their setups for the first time may find the outcome somewhat more sensual, polite and mild early on. In reality it’s not. Bass stripped from noise develops extra heft and fullness alright, but also becomes tighter and more powerful, so the opposite of what its earlier character would suggest. Instrumental outlines presented on a blacker backdrop may imply less overall radiance and clarity, while audibly more pronounced, weightier and longer in brilliance, contradicts this theory. More articulated and nuanced yet denser vocal lines don’t fully describe it either. The entire musical image grows larger and more robust, while edginess that causes listening fatigue vanishes. Unsurprisingly, the latest Firewall tailored for headphones follows this exact protocol to a tee. As such it introduces only audible gains.

If I had to narrow down the effect of the Firewall for Susvara cans to just a few bullet points tailored for the headfi audience, then we have this: more body, less pointy outline edges, less sharpness and less textural gloss, then followed by beefier tighter bass, more pronounced meatier midrange and far superior highs, particularly on decay and smoothness. Then again, this is grossly oversimplified. Atop all else it does, today’s Firewall also greatly boosts the sensation of aural space, so that it feels more breathing, moving and alive. This LessLoss also makes all tiny dust particles floating in air and the very last instrumental reverbs significantly easier to ‘see’ and appreciate. Clarity is yet again the key word. With cans as resolving as the Susvara, well, this single aspect massively gains on importance. The most interesting thing is that the major quality hike introduced in the process happens alongside the additional provision of substance, textures and body instead of it being in the least decreased in trade as is often the case. The elevated immediacy, energy, bite and snap follow.To frame the above into context somewhat easier to relate to, let’s go over a selection of tracks which proved useful in mapping what exactly today’s Firewall did for me. On Altın Gün’s funky “Kırşehirin Gülleri” and “Yekte” I heard primarily smoother and more distinct vocals. The same band’s trippy rousing song “Caney” sounded more clear and with extra bite to it, as if all its snappy jabs got shorter and more impactful in the process. Apocalyptica’s live take on “Orion” originally by Metallica had something different in store. About halfway through this song becomes soothing and gentle, just to gain momentum and energy near the end. With the LessLoss, the first part struck me as calmer, prettier and all in all fancier, while the energetic outro was noticeably more immediate, muscular and feistier. In other words, the two very distinct parts on that track had their specific quite opposite vibes pronounced better. I found that excellent.

Moving on, Arun Gosh’s peaceful melodic song “Nocturne” is built upon the key clarinet line that shows each note and air escaping that instrument in a very clear way. The Firewall extended these sounds a touch, which in turn made the entire tune more flowing, still calmer and dreamier. The same observations I had listening to Jon Lord’s “Miles Away” epic, which also benefited from the increased smoothness, ease, flow, juiciness and less compressed more distinct instruments. Individual bits on this tune registered as more pronounced sounds, which were again easier to follow and focus on. In effect the entire track registered as a more romantic and sensual version of itself with the LessLoss. This routine was repeated on “All Comers” by Mark Knopfler, albeit with noticeable gains on rhythm and swing, as if the main instruments’ individual notes were more on point.When the time came for my playlist’s guilty pleasures, the track “Writer in the Dark” by Lorde was my first choice, which with the Firewall engaged revealed a significantly better grip on bass and less coarse yet fleshier more articulated female vocal. Some sibilants still remained, but these are impossible to fully banish on this specific song no matter what we do. The fact that with the LessLoss I’d heard less of these pesky intruders sufficed to keep my ears happy and mark the clear quality bump. Einstürzende Neubauten’s “Magyar Energia” shifts our attention from vocals to bold spatial cues and occasional intense explosions out of nowhere which occupy the entire landscape. The Firewall injected more air into the view and dynamically expanded these roars to make them more sensible and instantaneous. Blixa Bargeld’s voice also struck me as more alive and here, while all the high-pitched sounds registered as quicker, somewhat uplifted, weightier and more shimmery. When I really want to hit the gas, “Danke” by IDLES covers that craving for me. Although this song is far from ideal recording wise, I still immensely enjoy it. Sinfully dirty, brutal, intense and energized are the words which entirely encapsulate how I see it. There’s a fine line between this high-octane well-caffeinated profile and all the claptrap “Danke”  embeds. With the Firewall it was less pointy, denser, wilder, more raw, articulated and blunt. Most importantly, the Lithuanian support made a hugely positive difference on this specific song. To my ears the sensation was comparable to listening to it on a floorstander armed with say two small cones, and i.e. Zu Audio DWX armed with one large paper membrane that needs very little power to pump lots of air very effortlessly. The way how such drivers speak the rock language makes them something entirely different on scale, directness and sheer entertainment. The LessLoss simply knew the dialect.

To close off, Francine Thirteen’s “Queen Mary” packs gargantuan imaging, clear calm vocal and deep bass hits atop occasional immediate dynamically wide hand claps. It had everything to fully communicate all the LessLoss’ features as clear as they were. The bass dug deeper, claps had more snap and body to them, the vocal was more substantial and lifelike and spatial sizing grew noticeably larger. The song felt more intense, enveloping and grander in spite of its somewhat slow-paced rhythm. At that point I had enough data to understand how much the Firewall actually did, and how beneficial it was. One last observation I had narrowed down to poorly recorded rock and metal fare which becomes too shouty and flat to enjoy at high SPL. A fair share of music i.e. by IDLES, Filter and Corvus Corax’s “Era Metallum” LP which I dearly adore fits here. The Firewall not only supported such repertoire as per the above, but it also allowed me to enjoy it at really loud volume. This was a personal win that I thoroughly appreciated.Lastly, it’s worth mentioning that 90% of my listening tests were conducted exclusively with a DIY-ed C-MARC headphone cable and pigtail. The listening sessions started with aftermarket equivalents based on Teflon-insulated high-grade silver-plated copper veins, which quickly fell short where it mattered. These aren’t bad cables per se, in comparison to Susvara’s stock leash they make a noticeable difference. It seems however that the Firewall box fancies the same manufacturer’s own noise-rejecting cables more. Or maybe they’re simply better on their own right? That’s a subject for another story and not mine to tell. Either way, to my ears the synergy between these products is high enough to see them as a system. I’ve been told that a commercially available headphone C-MARC is almost ready and several weeks away, so there’s that.

HifiMan Susvara’s equal generosity in terms of tone, color, spatial openness, feistiness, articulation and speed provision makes these cans a nicely balanced high-tiered specimen in my book. Considering how greatly the LessLoss Firewall elevated my experience with these universal planars, I can’t think of any other headphones which wouldn’t enjoy such company. You don’t want to pursue this posh exotic $4’918 booster right away, however. It’s clearly for those who rock fully sorted and locked upper-echelon setups built upon endgame power lines, decouplers, cables, DACs, amps and cans, yet still are inclined to push them further. If you don’t have that yet, look away. If you do and resources allow for further investments into your headfi rig, then at least sampling the LessLoss Firewall makes sense. The tech inside it has been around for years and proved highly effective for many people including yours truly. More importantly, it introduces gains which are very hard to come by elsewhere, especially at a dosage this high and for less coin. Personally I’m very happy that a Firewall device for cans is now a thing and every bit as effective as its awesome speaker siblings. Now you know that it’s here, my job’s done.

Associated Equipment:

Retail prices of reviewed components in EU (excl. VAT):

  • LessLoss Firewall for Headphones: $4’918

 

Manufacturer: LessLoss

 

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